How clean is an ISO Class 1 cleanroom

ISO1 Cleanrooms are the highest level of cleanrooms, with extremely strict requirements for air quality and particle concentration. A series of advanced technologies and measures are required to achieve this level.

Particle concentration

ISO1 modular cleanrooms have extremely low particle concentrations allowed in the air. According to ISO 14644-1 (International Organization for Standardization), the particle concentration of ISO1 cleanrooms should be less than or equal to the following levels:

•  0.1 micron particles: < 10/cubic feet

•  0.2 micron particles: < 4/cubic feet

•  0.5 micron particles: < 1/cubic feet

•  5.0 micron particles: < 0.1/cubic feet

Air cleanliness level

The air cleanliness level (ISO level) of A CleanRoom is based on the number of 0.1 micron to 0.5 micron particles per cubic meter of air:

ISO level = -log(number of particles/cubic meter)

ISO1 cleanrooms have an ISO level of 9. This means that the number of 0.1 micron to 0.5 micron particles per cubic meter of air is 10^-9.

Air Exchange Rate

In order to maintain the air cleanliness of an ISO Class 1 Cleanroom, a high air exchange rate needs to be maintained. This prevents particles from accumulating in the air. Depending on the cleanroom design standards, the air exchange rate for ISO1 cleanrooms is typically 500-700 times/hour.

Filter System

ISO1 cleanrooms use high efficiency air filters (HEPA filters) and ultra-low penetration Air Filters (ULPA filters) to remove particles from the air. These filters have a filtration efficiency of more than 99.99% and can remove more than 99.999% of 0.1 micron and 0.3 micron particles.

Pressure Gradient

ISO1 cleanrooms typically use a positive pressure gradient, which means that the air pressure inside the modular cleanroom is higher compared to the surrounding area. This pressure gradient prevents unfiltered air from entering the cleanroom and helps maintain cleanliness.

ISO1 cleanrooms are the highest cleanroom type with extremely stringent air quality and particle concentration requirements. By implementing strict control measures, including low particle concentration, high air exchange rate and advanced filtration system, ISO1 cleanrooms can provide highly controlled dust-free environment, suitable for key industries such as Semiconductor manufacturing, pharmaceutical and medical.

Related standards and specifications

• iso 14644-1: Cleanrooms and related controlled environments - Part 1: Terms and definitions

• iso 14644-2: Cleanrooms and related controlled environments - Part 2: monitoring methods

• GB/T 16290: Cleanroom specification